BMW six-cylinder engines have long been a byword for silky smoothness and zingy performance; the elastic surge of acceleration that gathered intensity as the tach needle swung past 4000 rpm, accompanied by that velvety snarl from under the hood, meant “The Ultimate Driving Machine” tagline was more than just clever advertising shtick.

But not every BMW six has been a home run. Remember the M20 eta engines? These torquemeister motors were designed to lug, not to rev, in the belief that the higher gearing they could pull would deliver vastly improved fuel efficiency. The etas were redlined at 4750 rpm, and sort of drove like diesels, except they were way smoother, and with lighter pistons and conrods, revved faster. Confused BMW drivers spent the whole time pounding the steering wheel in frustration as the etas smacked the rev-limiter just when they were expecting them to hit their stride.
BMW’s relatively new N55 straight six, now the mainline engine for the U.S. market, is no eta. But it’s most definitely not the sweetest six BMW has ever made. The N55 is technically impressive, boasting Valvetronic variable valve timing and an innovative twin-scroll turbocharger. It’s more efficient that its predecessor, yet delivers potent performance. So what’s the problem?

The problem is the N55 is almost impossible to drive smoothly in stop-start traffic. There is a strange hesitation in the power delivery when you accelerate from a standstill – almost as if the turbocharger has to spool – and then a big surge of torque arrives all at once. It’s the single most annoying characteristic of our N55-powered 535i GT long termer.

I’m still not sure whether this is purely a calibration problem; whether the BMW engineers haven’t
quite got the new ZF eight-speed auto trans to have a civilized conversation with the engine when you nail the gas or vice versa. But after driving the new BMW 535d in England, I suspect the problem might be the N55. Because BMW’s new 299 hp 3.0-liter turbodiesel hooked to the eight-speed ZF may just be one of the finest all-round passenger car powertrain combos in the business.

This engine is the third, and most powerful, version of BMW’s N57 common rail, direct injection, twin-turbo oil-burner, developing its 299 hp at 4400rpm, and a hefty 442 lb-ft of torque from just 1750 rpm. A low inertia small turbocharger delivers near instant grunt off idle, while a larger second turbocharger ensures volumetric efficiency at higher engine speeds.

Compared with the N55, the N57 delivers pure, seamless thrust right from standstill – even when you’re easy on the gas pedal – the ZF swiftly shuffling through its eight ratios. It’s perfect for the cut-and-thrust of London, where you’re constantly hustling for the smallest advantage in the traffic. The gobs of instant grunt mean rolling response on the freeway is impressive, too – just wiggle your big toe, and the 535d jumps to attention, allowing you to plug that gap in the fast moving stream of Benzes, Jags, and Range Rovers heading for the Home Counties on a Friday afternoon.

The N57 growls like a contented lion when you tickle the throttle, and there’s a slightly granular quality to the feedback from the engine room, but otherwise you lose nothing compared with the N55-powered 535i. At about 5.6 seconds the 535d’s claimed 0-60 mph time is virtually identical. More impressively, you’ll spend less at the pump, as BMW claims the 535d will return 36.3 mpg on the combined Euro cycle. We saw a best of 36.7 mpg for a 100-mile motorway run, and a worst of 23.5 mpg after 67 miles of stop-start running around the greater London area. Total consumption for our 1032 miles in the car was 30.2 mpg (all figures U.S. gallons). When a 13.8-gallon fill costs just over $120, such math is more than merely academic.

Part urban assault weapon, part trans-continental cruiser, the 535d is the best of the new 5-series models I’ve driven so far (the 550i I drove during our Car of the Year evaluation last year was spoiled by its slow, clunky, and noisy six-speed manual transmission). And most of the credit goes to the N57 turbo-diesel. It’s BMW’s best six.

Blasphemy? Heresy? All I know is, I would kill to have this upgraded engine and quick-shifting ZF 8 Speed in my car.

Blasphemy? Heresy? All I know is, I would kill to have this upgraded engine and quick-shifting ZF 8 Speed in my car.

I agree with that! More power and better mileage, i'll take it! I do find 8 gears to be too many too confusing, then again i've only experienced Audi's 8 speeder w/ the A4 and Q5 2.0T.

Today I opened up my d. It's been a while. I had punched it and was like damn this thing is fast but I was like eh, it's felt faster. later on i gave it a second go and put it all the way down right before the kick down and it kicked even harder! it has so much damn power! and my mpg's go up when i drive it harder if that makes any sense! lol. It's a very smooth engine with lots of power and efficiency. I love my 335d!

I agree, I used to be skeptical about the 8 speed, but I'm becoming more open to the idea, at least in a diesel. I feel like it would match the characteristics of the engine more than if it were mated to a gasser.

Another point to ponder is whether the engine output is accurate. Dynos suggest our 335d's are already producing around 300hp at the crank. So is this new engine really making more power or is it just more accurately rated?

Another point to ponder is whether the engine output is accurate. Dynos suggest our 335d's are already producing around 300hp at the crank. So is this new engine really making more power or is it just more accurately rated?

Well the new ones are rated @ 299/442, so it's probably just some mods (intake, possibly headers, exhaust, etc.) and some software. Doubt there's anything seriously different going on. Sort of how the 335is and Z4 sDrive35is (or whatever it's called) has a 15-20 hp difference...just a diff intake (and probably some software), even though the engine is essentially the same.

Read somewhere that the new 535d gets 46mpg highway...if accurate...that's pretty f'in insane. I know that conflicts with the quoted article, but just saying.

I had a 335d for a loaner yesterday and I could not believe the torque that thing had. Kinda sucks that its an auto because if you got caught it the wrong gear, it was a little sluggish. Once it found the sweet spot though, hold on to your socks! The pull was noticeably stronger than my 335i. I'd say BMW is pretty dumb to not put a 6 speed manual behind the turbo diesel. Plenty of people on this forum have already proved the trans can handle the torque.

I had a 335d for a loaner yesterday and I could not believe the torque that thing had. Kinda sucks that its an auto because if you got caught it the wrong gear, it was a little sluggish. Once it found the sweet spot though, hold on to your socks! The pull was noticeably stronger than my 335i. I'd say BMW is pretty dumb to not put a 6 speed manual behind the turbo diesel. Plenty of people on this forum have already proved the trans can handle the torque.

I honestly don't feel how it's sluggish in the wrong gear as torque is available at such a low RPM.

I am a big diesel fan and can't wait for the 335D's to start hitting the auctions as I will pick one up for a daily driver. I just wish they had AWD as an option. I have seen a couple of X5 35D's in the auction but for me, the price is a little steep. I will wait a year and I should start seeing them in the range for the vehicles I buy.

I currently also own a Jeep Grand Cherokee CRD S Limited. It could use the MB 7 Speed but for the most part it is an amazing truck. Lots of torque and decent MPG. It also has the QDII which is a fantastic AWD system. I would not have picked up a Jeep GC as a gas model.

I also had a 335D loaner this week, and took it out to some twisties during lunch - it has great low end grunt, the same balance as my 335. I was surprised how the diesel noise quieted down as it warmed up, and it has a nice growl under power.

The only thing I didnt like was the low redline, it was shifting a bunch in DS to keep it in the sweet spot. Such is life with a diesel - low redline = lots of shifts.

I didnt like how it shifted automagically at redline when I was using the paddles. I did like the paddles are now separate for upshift and downshift - much better setup than the one I had on the 2007 335iA.

I'd get one of these in a heartbeat at lease end if they brought the 330D in manual to the states.....likelyhood of it happening: zero

I noticed the article also misidentifies the 535d's engine: unless I've missed some new development, BMW's N57 is their latest diesel, but it is a single turbo used in the 330d and developing 245hp. The more powerful sequential turbo engines are designated M57 and they're actually not as new as the N57s. Given the 535d uses the sequential turbo setup, I think it's actually running a variant of the M57.

It's interesting how there's the same sort of "N55 vs N54" relationship between the two engines: the N57 is technically newer and more advanced, but the M57 seems to be the choice for BMW's more powerful models.

Well the new ones are rated @ 299/442, so it's probably just some mods (intake, possibly headers, exhaust, etc.) and some software. Doubt there's anything seriously different going on. Sort of how the 335is and Z4 sDrive35is (or whatever it's called) has a 15-20 hp difference...just a diff intake (and probably some software), even though the engine is essentially the same.

Read somewhere that the new 535d gets 46mpg highway...if accurate...that's pretty f'in insane. I know that conflicts with the quoted article, but just saying.

They need to get this to the states ASAP!!!

Seems like all BMW motors are underrated these days. The new N57 probably puts out 330hp or so at the crank.
The big question is whether the HP ratings will be the same in the US version. Today's US-spec 335d has lower peak power than the Euro version, though the torque is identical.

I wonder if that has to do with more restrictive exhaust, or maybe the motor is detuned slightly to work with the lowest common denominator of 40 cetane diesel in the US (whereas Europe is 51 minimum I think). From what I've read, Chevron diesel is consistently 47 or above so it's close to europe's fuel.

Seems like all BMW motors are underrated these days. The new N57 probably puts out 330hp or so at the crank.
The big question is whether the HP ratings will be the same in the US version. Today's US-spec 335d has lower peak power than the Euro version, though the torque is identical.

I wonder if that has to do with more restrictive exhaust, or maybe the motor is detuned slightly to work with the lowest common denominator of 40 cetane diesel in the US (whereas Europe is 51 minimum I think). From what I've read, Chevron diesel is consistently 47 or above so it's close to europe's fuel.

Personally, I've always been skeptical about the difference in power between the US and EU 335d's. The only difference is the urea exhaust injection, which isn't the sort of thing that should cost any horsepower. From the dynos I've seen they're all making right around 300 at the crank.

Personally, I've always been skeptical about the difference in power between the US and EU 335d's. The only difference is the urea exhaust injection, which isn't the sort of thing that should cost any horsepower. From the dynos I've seen they're all making right around 300 at the crank.

Personally, I've always been skeptical about the difference in power between the US and EU 335d's. The only difference is the urea exhaust injection, which isn't the sort of thing that should cost any horsepower. From the dynos I've seen they're all making right around 300 at the crank.

I think the cetane rating of the fuel could matter. Lower cetane fuel doesn't burn as quickly which could affect the amount of power you get at higher RPM's. Since the US only requires 40 cetane as a minimum, maybe the HP ratings take that into account?